But you always need to be careful!!
I dont think 1.65x martingale is a great multiplier on it. It just depends on your luck when it comes to dice game. What I can say it 2x multiplier is the best thing to do. Because if you win it will double it. Let say base 1btc 2x you will get 2 btc then if you lose you will only lose 1btc. If you use 1.65x you win 0.65 but if you lose you will lose 1btc, it is not worth to bet like that. You need at least bet 2 times to double it and it will double your chances to lose
That is not an issue at all. Let's say if your bet multiplier is m, you should increase your bet size by a factor of 1/(m-1) upon a losing bet when you want to get a fixed profit upon a winning bet.
For example, for a multiplier of x2, you should increase your bet size by 100%; for x3, the increase should be 50%; for x1.5, it should be 200%; and for x1.65, it should be 154%.
The only issue of it (and all variations of martingale) is you will eventually hit a long enough losing streak and lose all your balance.